36th International Carrot Conference Abstract

Calorespirometry: a new tool for phenotyping carrot genotypes for cold tolerance and functional marker development

Amaia Nogales¹, Luz Muñoz-Sanhueza¹, Lee D. Hansen², Birgit Arnholdt-Schmitt¹

¹EU Marie Curie Chair, ICAAM – Instituto de Ciências Agrárias e Ambientais Mediterrânicas, Universidade de Évora, Nucleo da Mitra, Ap. 94, 7002-554 Évora, Portugal.

²Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA

Among abiotic environmental stresses, low temperature is one the main factors that affects plant growth and crop yield most seriously. During the last years plant breeding has focused much attention to the identification of molecular markers associated with cold tolerance that will contribute to an efficient selection of elite genotypes with superior cold hardiness.

While the development of high-throughput genotyping platforms has considerably increased the efficiency of plant genotyping and molecular marker search, the screening process of plant populations for desirable traits is still the most laborious and technically challenging part.

In this work, we propose a new strategy for the development of functional markers for cold tolerance. Calorespirometric measurements of metabolic heat rates and CO₂ production rates as a function of temperature enable rapid determination of the temperatures which plants are adapted to without growing them in different environmental temperatures. This feature of the technique makes it a good candidate to be used as a tool to perform pre-screenings of new carrot genotypes for low temperature tolerance in short period of time, increasing by this way the efficiency of phenotyping. This technique has enabled to discriminate different carrot phenotypes based on their temperature response and thus, it allows to do a pre-selection of the genotypes that are most interesting to be tested for their cold resistance, by this way saving time and money.

Functional marker (FM) approach involves the study of polymorphisms in the DNA sequences that cause functional differences in the host gene. In the case of low temperature adaptation studies, alternative oxidase (AOX) gene has been proposed as a candidate gene for FM search. AOX gene expression is known to increase in response to low temperature stress, and mutations within the gene sequence has been shown to be related with differential cold tolerance at least in rice and tomato.

If validated, calorespirometry may aid in two ways: in the identification of cold tolerant genotypes and in increasing the efficiency of the association studies between the potential FM in the AOX gene sequences and cold tolerance by facilitating the phenotyping task of different carrot AOX polymorphic genotypes.

Acknowledgements:

This work is funded by FEDER Funds through the Operational Programme for Competitiveness Factors - COMPETE and National Funds through FCT - Foundation for Science and Technology under the Strategic Project PEst-C/AGR/UI0115/2011 and the Project EXCL/AGR-PRO/0038/2012 (FCOMP-01-0124-FEDER-027385). The authors would like to thank to FCT for the support given under the program POPH – Programa Operacional Potencial Humano (Ciência 2007).

Last updated Thursday, 25-Jul-2013 11:51:32 CDT